A quick-frozen, freeze-fracture and deep-etched study of the cuticle of adult forms of Strongyloides venezuelensis (Nematoda)

Parasitology ◽  
1995 ◽  
Vol 111 (4) ◽  
pp. 523-529 ◽  
Author(s):  
A. M. B. Martinez ◽  
W. De Souza
Keyword(s):  
Body Wall ◽  
Amorphous Matrix ◽  
Freeze Fracture ◽  
The Body ◽  
Fibrous Layer ◽  
Thin Sections ◽  
Parallel Lines ◽  
Transmission Electron ◽  
Strongyloides Venezuelensis ◽  
Ordered Array

SUMMARYThe cuticle of adult forms of Strongyloides venezuelensis was studied by routine transmission electron microscopy, conventional freeze-fracture and also using quick-freeze and deep-etch techniques. In routine thin sections the cuticle of S. venezuelensis comprises 7 layers: epicuticle, outer cortical, inner corticcal, external medial, internal medial, fibrous and basal. Observation of replicas of specimens fractured across the thickness of the body wall, revealed at the epicuticle an ordered array of particles accompanying the cuticular annulations. At the level of the cortical and medial layers we observed few scattered particles embedded in an amorphous matrix without a particular arrangement. The fibrous layer was represented by several parallel lines of ordered particles of similar size. In tangentially fractured specimens, the epicuticle cleaves readily exposing 2 faces, one exhibiting intramembranous particles without any particular arrangement, immersed in a smooth matrix (P face), and the other showing depressions and very few particles (E face). In replicas of fractures submitted to etching, we observed at the level of the cortical, medial fibrous and basal layers an interconnecting fibrous and globous structure which was organized in a different direction at the fibrous layer. The association of freeze-fracture to deep-etch technique revealed the internal structural organization of the cuticle layers showing details that were not seen before using conventional freeze–fracture technique.

Some ultrastructural aspects of Crithidia guilhermei n.sp. isolated from Phaenicia cuprina (Diptera: Calliphoridae)

1986 ◽  
Vol 64 (12) ◽  
pp. 2837-2842 ◽  
Author(s):  
Maurilio J. Soares ◽  
Reginaldo P. Brazil ◽  
Amilcar Tanuri ◽  
Wanderley de Souza
Keyword(s):  
Freeze Fracture ◽  
Kinetoplast Dna ◽  
Microscopical Level ◽  
Thin Sections ◽  
Crithidia Luciliae ◽  
Transmission Electron ◽  
Light Microscopical Level ◽  
Attachment Region ◽  
Phaenicia Sericata ◽  
A New Species

A flagellate trypanosomatid was isolated from the fly Phaenicia cuprina captured in Rio de Janeiro, Brazil. It grows well in liver infusion – trypticase medium, in the form of choanomastigotes, typical of the genus Crithidia. Morphometrical data obtained at the light microscopical level indicated that the new isolated Crithidia is smaller than Crithidia luciliae, a parasite isolated from Phaenicia sericata. Transmission electron microscopy of thin sections revealed that this trypanosomatid has a flagellar pocket divided into two compartments, one basal and the other apical, separated by a region of attachment of the flagellum to the cell body. The attachment region was characterized in freeze-fracture replicas. The flagellate has a compact kinetoplast DNA network. As in endosymbiote-containing trypanosomatids previously described, no subpellicular microtubules were seen in the regions where the mitochondria touched the plasma membrane, although no endosymbiotes were found in this flagellate. Electrophoretic mobility of six enzymes showed that the parasite could not be grouped in any of the isoenzymic pattern groups of other Crithidia spp. These observations indicate that the trypanosomatid isolated from P. cuprina is a new species of Crithidia. The flagellate is described as Crithidia guilhermei n.sp.

Ultrastructure of graniferous tracheary elements in the haustorium of Exocarpus bidwillii , a root hemi-parasite of the Santalaceae

1979 ◽  
Vol 204 (1156) ◽  
pp. 329-343 ◽  
Keyword(s):  
Xylem Sap ◽  
The Body ◽  
Fibrillar Structure ◽  
Tracheary Elements ◽  
Thin Sections ◽  
Successive Layer ◽  
Transmission Electron ◽  
Vessel Elements ◽  
Homogeneous Matrix ◽  
Dispersed Material

The xylem in the body of the haustorium of E. bidwillii has the shape of an inverted conical flask with the expanded portion being known as the vascular core. The tracheary elements of the vascular core are notable for the occurrence of numerous granules within their lumina and the presence of mostly imperforate walls. Elsewhere in the haustorium graniferous tracheary elements are absent and the cells are usually ordinary vessel elements. Thin sections for transmission electron microscopy, post-stained in potassium permanganate, show that the secondary wall thickenings of the graniferous tracheary elements consist of eccentric layers in which the microfibrils of each successive layer run alternately longitudinally and transversely. The granules of the tracheary elements average 2 μm in diameter and consist of a homogeneous matrix which shows a fine fibrillar structure on high resolution. The granules are naked and mostly remain as separate structures within the lumen of the cell, but occasionally they fuse into small groups or irregular masses. In some cells the granules become transformed into fibrillar material that disperses throughout the lumen. This dispersed material may accumulate in vessels of the interrupted zone proximal to the vascular core. Occasionally, the granules also change into compacted amorphous masses that adhere to the walls of the cell. Ultrastructural cytochemistry confirms that the granules are protein and not starch as was originally believed for the Santalaceae. The function of the vascular core and its graniferous tracheary elements is discussed and we suggest that it might help regulate the pressure and flow of xylem sap entering the parasite from the host. Graniferous tracheary elements in the Santalaceae and in root parasites of the Scrophulariaceae are compared and it is concluded that they represent examples of convergent evolution.

scholarly journals Particle arrays in earthworm postjunctional membranes.

1978 ◽  
Vol 76 (1) ◽  
pp. 76-86 ◽  
Author(s):  
J Rosenbluth
Keyword(s):  
Cell Membrane ◽  
Muscle Cell ◽  
Acetylcholine Receptors ◽  
Body Wall ◽  
Freeze Fracture ◽  
Body Wall Muscle ◽  
Thin Sections ◽  
Ordered Arrays ◽  
Accurate Picture ◽  
Muscle Cell Membrane

Analysis of freeze-fractured earthworm body wall muscle reveals distinctive trough-shaped concavities in the protoplasmic leaflet of the muscle cell membrane which contain diagonally oriented rows of particles sometimes in highly ordered arrays. The troughs correspond to the concave postjunctional patches of sarcolemma seen previously in thin sections of myoneural junctions identified as cholinergic, and the intramembranous particles within the troughs correspond in concentration and arrangement to granular elements present in the outer dense lamina of the postjunctional membrane which were interpreted as acetylcholine receptors. The freeze-fracture data provide a more accurate picture of the arrangement of these putative receptors within the plane of the membrane, and indicate also that they extend into the membrane at least as far as its hydrophobic layer.

Capture of nematodes by Arthrobotrys oligospora, an electron microscope study

1978 ◽  
Vol 56 (10) ◽  
pp. 1297-1307 ◽  
Author(s):  
Birgit Nordbring-Hertz ◽  
Margaretha Stålhammar-Carlemalm
Keyword(s):  
Electron Microscope ◽  
The Body ◽  
Fungal Culture ◽  
Arthrobotrys Oligospora ◽  
Thin Sections ◽  
Transmission Electron ◽  
Transmission Electron Microscope Micrographs ◽  
Nematode Cuticle ◽  
Nematode Penetration ◽  
Dense Vesicles

The capture of nematodes by Arthrobotrys oligospora consists of (1) firm adhesion of the nematode to the capture organ, (2) penetration of the nematode cuticle by a penetration hypha, and (3) digestion of the nematode. Penetration of the nematode cuticle by a penetration hypha originating from the trap took place within 1 h after addition of nematodes to a fungal culture and occurred at any point on the nematode surface. Vegetative hyphae were able to invade an immobilized nematode only through the body orifices (8–12 h after addition of nematodes to fungal cultures lacking traps). The presence of prey caused an increased secretion of adhesive from the trap. Scanning electron microscope micrographs show a captured nematode covered by a mucilaginous coat. In transmission electron microscope micrographs of thin sections, a distinct osmiophilic layer between trap and nematode is always present. Since penetration occurred at the point of deposit of these substances, it is suggested that the osmiophilic layer also has enzymatic activity. An osmiophilic layer was never seen around vegetative hyphae, indicating the lack of both adhesive and similar enzymes.The traps contained numerous membranous electron-dense vesicles (150–300 nm) not present in hyphae. Large osmiophilic inclusions (1–2 μm) were more common in traps at certain stages of development than in hyphae. The results indicate that the adhesive and the digestive enzymes originate from either or both of these organelles.

The fine structure of the germinal mass, brood cavity and birth canal of the rediae of the monoxenous hemiuroid digenean Bunocotyle progenetica Chabaud & Buttner, 1959

2019 ◽  
Vol 94 ◽  
Author(s):  
I.M. Podvyaznaya ◽  
A.A. Petrov ◽  
K.V. Galaktionov
Keyword(s):  
Fine Structure ◽  
Life Cycle ◽  
Body Wall ◽  
The Body ◽  
Cellular Composition ◽  
Birth Canal ◽  
Offspring Number ◽  
Transmission Electron ◽  
Reproductive Apparatus ◽  
Germinal Mass

Abstract Bunocotyle progenetica is a hemiuroid digenean whose sexual adults become fully developed and lay their eggs inside the rediae in the molluscan host. In this study, the fine structure of the germinal mass, brood cavity and birth canal in the B. progenetica rediae was examined using transmission electron and confocal microscopy. The large germinal mass attached to the body wall has a cellular composition typical for this organ. The characteristic traits of this germinal mass are weakly developed supporting tissue and the presence of deep lacunae opening into the brood cavity. These lacunae presumably participate in feeding the deeply lying embryos and facilitate their release into the brood cavity. The germinal mass is also characterized by intensive degeneration of cellular elements, which may represent a mechanism controlling the offspring number, limited in this species by the size of the redial brood cavity. The brood-cavity lining consists of flattened cells bearing lamellar projections and is connected anteriorly with the epithelium of the birth canal. The brood-cavity musculature, which is well developed in other hemiuroid digeneans, is significantly reduced in B. progenetica, most likely because their cystophorous cercariae remain inside the rediae, removing the need for muscle contractions pushing them through the brood cavity. The birth canal comprises three regions distinguished by the structure of the lining and muscle arrangement. The comparison of rediae of B. progenetica with parthenitae of other digeneans has shown that the organization of the redial reproductive apparatus in this species may have been influenced by life-cycle modification.

Cephalic sense organs and body pores of Xiphinema americanum (Nematoda: Dorylaimoidea)

1980 ◽  
Vol 58 (8) ◽  
pp. 1439-1451 ◽  
Author(s):  
K. A. Wright ◽  
R. Carter
Keyword(s):  
Body Wall ◽  
The Body ◽  
Sheath Cell ◽  
Sense Organs ◽  
Microtubule Organizing Center ◽  
Transmission Electron ◽  
Organizing Center ◽  
Cell Processes ◽  
The Central Nervous System ◽  
Internal Sense

The fine structure of the cephalic sense organs and body pores of the plant parasitic nematode Xiphinema americanum is described by transmission electron microscopy. All of the six inner labial, six outer labial, and four cephalic sense organs as well as the amphids have characteristics indicating chemosensitivity, but there are no clearly identifiable mechanosensitive units. Two pairs of simple internal sense organs, not associated with cuticle, also occur. Sensory dendrites all bear cilium-derived dendritic processes that contain axonemal doublets of microtubules. These doublets show radial and circumferential linkages characteristic of the ciliary necklace region of a cilium, although only an amorphous microtubule organizing center occurs in the usual place of a basal body.Both socket cell and sheath cell processes are associated with the cuticular sense organs. The cell body of the amphidial sheath cell is located well anterior to the central nervous system, before the level of the buccal dilator muscles.Body pores are associated with sensory units characteristic of chemosensitive organs. Hypodermal cells serve as their socket cells, whereas a separate sheath cell occurs in the body wall close to each pore.

scholarly journals Ultrastructure of the buccal capsule in the adult female Anguillicoloides crassus (Nematoda: Anguillicolidae)

2010 ◽  
Vol 47 (3) ◽  
pp. 170-178 ◽  
Author(s):  
M. Bruňanská ◽  
H. Fagerholm ◽  
F. Moravec ◽  
Z. Vasilková
Keyword(s):  
Adult Female ◽  
Cross Sections ◽  
Body Wall ◽  
Buccal Capsule ◽  
The Body ◽  
Transmission Electron ◽  
Junctional Complexes ◽  
Marginal Cells ◽  
First Time ◽  
Anguillicoloides Crassus

Abstract The fine structure of the buccal capsule of the adult female nematode Anguillicoloides crassus (Spirurina) was studied for the first time. Results are based on serial section (longitudinal and transverse) light and transmission electron microscopy. The buccal capsule of A. crassus is a cuticular-lined structure. It can be divided into three main parts: cheilostom, gymnostom and stegostom. The cheilostom is the anterior region of the buccal capsule with the cuticular lining continuous with the body wall cuticle and underlain by epidermal syncytia. The gymnostom is a cuticular region with portions of it very electron dense and underlain by arcade syncytia. A dense circumoral cylinder together with the circumpharyngeal ring represent the prominent characters of the gymnostom. The stegostom is formed by anterior pharyngeal cuticle underlain by muscular radial cells and epithelial marginal cells. The cephalic cuticle of A. crassus makes a direct contact with the pharyngeal cuticle at the base of the circumoral cylinder, within a circumpharyngeal ring containing projections of pharyngeal muscular and marginal cells. The circumoral cylinder, circumpharyngeal ring and pharynx are connected to the body epidermis by junctional complexes. The buccal capsule includes occasionally 3 projections of the pharynx evidently observed in serial cross sections. These ultrastructural characters may provide useful data for comparative, functional as well as evolutionary studies within the Chromadorea.

Ultrastructure of the dormant and germinating sporangiospore of Phascolomyces articulosus (Mucorales)

1978 ◽  
Vol 56 (7) ◽  
pp. 747-753 ◽  
Author(s):  
P. Jeffries ◽  
T. W. K. Young
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Freeze Fracture ◽  
Spore Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Transmission Electron ◽  
Sporangial Wall ◽  
Scanning Electron

Using results obtained with light and scanning electron microscopy of critical-point-dried material and transmission electron microscopy of carbon replicas and freeze-fracture and ultra-thin sections, the structure and germination of the sporangiospore of Phascolomyces articulosus Boedijn is described. The sporangial wall is trilaminate and the ornamented spore wall is two layered. During germination, a new wall layer develops between the plasmalemma and the original spore wall. Sporangial structure is related to that of other members of the Thamnidiaceae and the use of germinating spores of P. articulosus for infection studies of the mycoparasite Piptocephalis unispora is indicated.

Intercellular junctions in the larval epidermis of the colonial ascidian Distaplia occidentalis: a thin-section and freeze-fracture examination

1986 ◽  
Vol 64 (1) ◽  
pp. 112-117 ◽  
Author(s):  
Michael J. Cavey ◽  
Richard L. Wood
Keyword(s):  
Electron Microscopy ◽  
Freeze Fracture ◽  
Intercellular Junctions ◽  
Epidermal Cells ◽  
Cellular Membranes ◽  
Colonial Ascidian ◽  
Thin Sections ◽  
Intramembranous Particles ◽  
Transmission Electron ◽  
Columnar Cells

The larval epidermis of the colonial ascidian Distaplia occidentalis is a unilayered epithelium consisting of squamous and cuboidal or low columnar cells. The epidermal cells are laterally folded and interdigitated or overlapped. The occluding (tight) junctions and the close (gap) junctions that join the epidermal cells have been examined by transmission electron microscopy. In thin sections, the occluding junction is represented by focal fusions of the apposed plasmalemmata. Freeze-fracture replicas of the occluding junction show linear, anastomosing arrays of intramembranous particles on the protoplasmic faces of the cellular membranes. In thin sections of the close junction, the apposed plasmalemmata are mutually parallel and separated by a narrow intercellular cleft. Freeze-fracture replicas of the close junction reveal macular aggregations of intramembranous particles on the protoplasmic faces of the cellular membranes.

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